Suppression of superconductivity by injection of spin-polarized current

We present results demonstrating that the superconductivity in thin films can be strongly influenced by the injection of a spin-polarized current from a magnetic material. The effect has been found to occur in both low T-c (Sn) and high T-c (YBa2Cu3O7-delta) superconductors when either a ferromagnetic material, permalloy (Ni0.8Fe0.2), or a collosal magnetic material LaSrMnO is used as the source of spin polarization. Control experiments showed that unpolarized current from a nonmagnetic metal had comparatively little effect on the same superconductors. A phenomenological model in which the energy gap of the superconductor is strongly perturbed by the presence of excess spin polarized electrons is found to mimic the experimental results.